The present invention relates to three-dimensional displays and specifically to a three-dimensional display system which incorporates a vibrating reflective MYLAR plane upon which is projected a spatially encoded laser generated image where the vibrating reflective MYLAR plane serves to decode the laser image creating a three-dimensional display of that image.
Over time a number of apparata have been addressed to the creation of a three-dimensional image upon a two-dimensional plane, such as a projection screen or television cathode ray tube. Several of the prior art systems have incorporated varifocal mirrored surfaces to generate the three-dimensional image. The varying focal length of the mirror is typically achieved by physically vibrating the mirror about the axis perpendicular to the plane formed by the mirror. While several of these prior art systems have incorporated varifocal mirrors composed of a thin reflective MYLAR film stretched over a loudspeaker, the image projected thereon has been almost exclusively generated by a conventional cathode ray tube (CRT). In such devices, the image to be viewed in a three-dimensional fashion is provided by the cathode ray tube after having been generated in a conventional manner. The CRT image is then presented to the surface of the vibrating mirror such that the reflection of the image in the vibrating mirror is constantly swept back and forth as the mirror oscillates. The persistence of vision of the human observer causes the discrete images to fuse together, thus creating the three-dimensional display.
Such a system is described in such patents as M. C. King, U.S. Pat. No. 3,632,184; M. C. King, U.S. Pat. No. 3,632,866; and L. D. Sher, U.S. Pat. No. 4,130,832. Unfortunately however, such prior art imaging apparata which rely upon a CRT to present the image to the vibrating mirror have experienced drawbacks which make such systems wholly inadequate in certain applications. The limitation of such prior art systems stems from the use of the CRT to originate and project the desired three-dimensional image. It will be recognized by those skilled in the art that the image appearing to an observer on the surface of the CRT is made possible because the phosphor material lining the interior of the CRT glows upon being struck by the electron beam generated within the tube. It is because of the persistence of these phosphors, i.e. the lag time during which the phosphor continues to glow after the electron beam passes, that the observer is able to view the complete image since the electron beam is constantly sweeping across the CRT striking only a single point at any given time. Absent the persistence of the phosphors only a single point on the CRT would be illuminated at any time. Since the time to scan the entire face of the CRT exceeds the viewer's persistence of vision a poor display would result but for the phosphor lag time. It should also be noted that certain high brightness phosphors may have decay patterns which exceed the moment of observation by many orders of magnitude. It is this phosphor persistence and lag time, which makes such prior art systems unsuitable for certain applications as long lag times may occur when it is essential to erase the image being presented. The inherent limitation of such prior art systems stemming from the phosphor to mirror interface and the associated flouresing lag time makes it difficult to instantly erase the image appearing on the CRT and thus the displayed three-dimensional image. While advances have been made in the development of "high speed" CRTs which minimize the phosphor lag time, while still providing sufficient persistence to permit normal viewing, the fluoresing lag time present in such "high speed" CRTs is nevertheless still so long as to prohibit erasure of the display as desired. In addition to the erasure problem, the lag time present in the CRT interface seriously limits the resolution of the three-dimensional display produced since fewer complete images can be generated within a given time period due to the time required by the CRT to sweep out a complete screen.
It can be seen that the CRT's inability to erase the image presentation with sufficient speed may make such systems unsuitable for applications where the image being viewed changes rapidly and the ability to isolate and otherwise view such change is critical.
The three-dimensional laser driven display apparatus disclosed herein has application in many areas. For example, the three-dimensional laser driven display apparatus may be used in air traffic control tower settings where the data pertaining to an approaching aircraft's glide path and relative position coordinates may both be viewed upon a single three-dimensional display rather than requiring the air traffic controller to view two separate radar screen images as is currently the practice. The present invention similarly has great usefulness in the area of "head-up" displays, particularly in military jet fighters where a three dimensional display of a target or an incoming missile and the selective display capabilities of the present invention can greatly enhance the fighter and pilot's performance. Still further, the ability of the present invention to project and display a three-dimensional image in space apart from a fixed two-dimensional projection screen makes possible the creation of decoy objects. Through the present invention for example, military hardware or even troops may be projected onto a battlefield and viewed as if they were actually there when in fact no physical object exists. Still further, decoy aircraft could be made to appear in flight when none are present. Of significant potential is the ability to operate the data acquisition facet of the present invention with an infrared laser which can serve, in certain circumstances, to overcome the stealth capability of modern military aircraft and ships. The ability to acquire image data and display corresponding three-dimensional images has powerful medical applications in the area of exploratory medicine. The present invention also has application in the field of cryptography as a cryptographic generation device due to its flexible sophisticated encoding and decoding capabilities.
Accordingly it is the object of the present invention to provide a three-dimensional laser driven display apparatus which utilizes laser beams as the principal image source which is viewed using a vibrating mirror structure, thereby eliminating the CRT's phosphor dependency and permitting instant erasure of the image and observation of minute changes therein.
It is additionally an object of the present invention to provide such a three-dimensional system where the pulse width of the laser and the spatial interactions permit a point to be located on the vibrating mirror which is presented in an exact phase condition with the image signals driving the laser.
It is a further object of the present invention to provide laser beams of different colors where various colored laser beams may be combined with one another to generate blanking techniques which can eliminate or alternatively enhance specific characteristics of the three-dimensional presentation.
An additional object of the present invention is to provide for the projection of a three-dimensional laser driven display offset from the varifocal mirror means.
Yet a further object of the present invention is to provide for the viewing of the three-dimensional laser driven display directly upon the varifocal mirror means through the use of an intermediate imaging surface means.
It is yet another object of the present invention to provide a data acquisition mechanism which utilizes fiber optics permitting exploration of cavities of the human body towards the three-dimensional viewing thereof.
It is another object of the present invention to provide such a three-dimensional system which incorporates a reflective MYLAR mirror having ferrite material deposited thereon such that an electron beam sweep may produce magnetic attenuation of the mirror toward the selective enhancement or modification of the three-dimensional image being reflected therefrom.
It is yet another object of the present invention to provide such a three-dimensional system which includes a MYLAR film having phosphor material deposit thereon where such phosphor material is sensitive to selective x-ray or ultraviolet light so as to permit the use of non-visible lasers.
As a further object of the present invention, an imaging surface may be provided to cut the level of laser radiation or otherwise non-optically control or modify the image to be displayed.
Still another object of the present invention is to provide a three-dimensional system incorporating a vibrating mirror assembly which includes laser detectors to permit the modification or enhancement of the three-dimensional image as a function of the color, frequency, phase or power of the laser image reflecting off of the MYLAR film.
It is yet a further object of the present invention to provide image enhancement techniques whereby various waveforms as well as standing waves may be generated upon the reflective MYLAR film to alter the spatial characteristics of the three-dimensional display.
These and other objects of the invention will become apparent in light of the present specification and drawings.